Combined telephone and fire alarm system



/N VE N TOR Rca/Momm- -June 21,A 1938. R2 c. BRADFORD l COMBINED TELEPHONE AND FIRE ALARM SYSTEM ,Filed Deo. 12, 1936 Patented June `21, 1938 -UN1TED STATES COMBINED TELEPHONE AND FIREl ALARM SYSTEM Raymond Carter Bradford, Hamden, Conn., as-

signor to American Telephone and Telegraph C'ompany,.a corporation of New York Application December 12, 1936, Serial No. 115,602I

10 Claims.

`This invention relates to systems of remote control land particularly to combined telephone and fire alarm signaling `systems and constitutes an improvement Aover a similar system disclosed inzthe patent `application of 'R'. C. Bradford,

Serial No. 4,545, A-iiled February l, 1935.

flnthe above-identiied application there is disclosed'a system `of remote control in which a telephone line circuit, normally adapted for the transmission Ofspeechcurrents between a central oiiice and subscribers station, is utilized as the medium over which signaling devices located at a point remote from lthe central office maybe controlled by a central oiiice operator.

It is the object `of this invention to provide an lmprovedsystem of the above character.

\ This object is attained in accordance with a feature of the invention b y the provisionof means ist'I at the subscribers station for rendering possible the actuation of a fire alarm signal by the subscriber, which heretofore, was capable of operation `only Aby an operator at theI telephone exchange.

Another feature of the invention resides in a circuit arrangement whichpermits a central cnice operator to eiect the operation of the lire alarm for test purposes and to subsequently silence the alarm Without causing the operation of the stationsignal `to give a false ringing signal.

These and other features of the invention will be readily understood from the following detailed description made `with reference to the accompanying drawinggwhich discloses `the telephone line lcircuit L of this invention andan operators cord circuit'C and associated equipment, by virtue of which signalingequipment located at a substationfS and at a point remote from the substation may be controlled. V

"The IlineL terminates at the central ofce in a lpairofkiaclrs, one of `,which is utilized by the operator in establishing a telephone connection with-the substation S which is provided with the usual type ringer I and telephone set, and the other of which is employed by the operator in transmitting a fire ysignal to the station S or to somefremotepoint at which the fire siren 20 is located. The station S may be vlocated `at a fire headquarters lor llire house and the siren 20 may constitute part of the station equipment or may be located at somel central point in a locality in'` which the lire headquarters or re house is situated. A monitoring microphone 30 located in closelproximity to thesiren 20 is furnished for a purpose which willrbe indicated hereinafter.

*"Ifheinvention -will be best understood from the following detailed description of the operation of the system disclosed in the drawing.

Assuming that an operator at a central oce desires to establish a telephone connection With the substation S, she inserts the calling plug II of` a cord circuit, such as C, into the jack I2 associated with the line circuit L which is individual to the station S, and actuates a ringing key I3. A circuit is thereupon established which may be traced from the grounded ringing current source I4, lower alternate contacts of key I3, `ring contacts of plug II and jack I2, conductor I5, normal ring contacts oijack I6, ring conductor I1 of line L, condenser I8, winding of relay I9, lefthand section of repeating coil 2I, tip conductor 22 of line L, normal tip contacts of jack I6, conductor 23, `tip contacts of jack I2 and plug II to ground by way of the upper alternate contacts of key I3.

Relay I9 operates in this circuit and at its armature and armature contact establishes an obvious energizing circuit for relay 2l!- Which relay operates causing the substation end of the line circuit L to be disconnected from the right-hand section of repeating coil 2I and connected directly `to the jack terminals.

Relay 25 now operates in a circuit `extending Afrom ringing current source I4, lower alternate contacts of ringing key I3, ring contacts of plug II and jack I2, conductor I5, normal ring contacts of jack I6, ring conductorll of line circuit L, conductor 26, front contact and lower armature of relayl 24, winding ofrelay 25, condenser 21, conductor 64, upper armature and front contact of relay 24, conductor 3l, tipconductor 22 of line circuit L, tip contacts of jack I6, conductor 23, tip contacts of jack I2, and plug I I to ground at the upper alternate contacts of key I3. Relay 25, in operating, connects the ringer I0 and the winding of relay 4I] to the ring conductor `of the line circuit L by way of its right-hand armature and front contact, and at its left-hand armature and front contact it connects relay 2li to the tip side of the line. Relay 4D and ringer Ill operate at this time. It will be noted that the tip side of the line L is grounded at the upper alternate contact of key I3 so that relay 28 is effectively shunted and therefore does not operate at this time. The ringer I0 and relay 40, as before stated, however, being connected to the ring side of the line operate on current from the source I4. Relay 4B, however, merely preparesa shunt path `from ground on the conductor 6I to the right-hand front contact of relay 40 to the ring side of the line and at its outer armature and front contact connects the windrelay to lock out relay G2 and prevent it from accidentally operating on cross-ring surges.

In response to the actuated signal I0, the handset 9 at station S is removed from its switchhook, eiectively bridging the telephone set across the line L in the well known manner. Removal of the receiver shunts relay 25 which releases should the attendant continue to ring after the receiver is removed from the switchhook.

Relay 3| now operates in a circuit extending from grounded battery, lament of lamp 32A, conductor 33, lower winding of relay 3|, lower right-hand winding of repeating coil 2|, back contact and lower armature of relay 24, conductor 53, through the closed subscribers line loop, conductor 35, upper armature and back contact of relay 24, upper right-hand winding of repeating coil 2| to ground through the upper winding of relay 2| and filament of lamp 32. Relay 3| operates in this circuit, short circuits the condenser 48 and completes the ring side ofthe line. An indication of the response of the subscriber is given to the attendant by a supervisory lamp (not shown) in the cord circuit C which is lighted by theoperation ofra cord supervisory relay (not shown). The cord supervisory lamp operates as a consequence of the closed supervisory loop through resistance 50 and the armature contacts of relay 3|.

If the operator desires to communicate with the subscriber, she actuates talk key 3E which connects her telephone set across the cord circuit C. At the termination of the conversation, the operator withdraws plug |I from jack I2 and the subscriber at station S replaces the receiver on its switchhook whereupon the operated relays release and the circuit restores to normal.

Should the central ofce operator wish to broadcast a fire signal, she proceeds in the manner hereinbefore described in signaling a subscriber at station S except that the alarm jack I6 is employed in place of the jack I2.

The actuation of ringing key I3, as in the previous case, causes relay I9 to operate and close an obvious circuit to relay 24. Relay 24, operated, excludes the repeating coil 2| from the ringing circuit and connects relay 25 directly to the jack terminals of the line L. Relay 25 operates and at its right-hand armature and front contact connects ringer I0 and the winding of ing of relay 28 to the tip side of the line. Relay 40 and the ringer I0 are effectively shunted and do not operate.

Relay 28, however, does operate in a circuit extending from the source |4, lower alternate contacts of key I3, ring contacts of plug II and jack I6, tip side of line L, conductor 3l, front contact and upper armature of relay 24, conductors 64 and 65, front contact and left-hand armature of relay 25, condenser 66, winding of relay 28, conductors 61 and 6| to ground. Relay 28, operated causes relays GII) and 62 to operate in series in a circuit extending from grounded battery, winding of relay 60, conductor 68, winding of relay 62, front contact and armature of relay 28, conductors 61 and 6I to ground. At its inner left-hand armature relay 62 establishes an obvious locking circuit for itself and relay 6D. At its outer right-hand armature and front contact relay 62 connects the right-hand winding coil and the monitoring microphone 30 in series to ground and battery. At its inner right-hand armature and front ycontact relay 62 connects the left-hand winding of coil 44 across the tip and ring conductors of the line L. At its outer left-hand armature and front contact relay 62 connects the siren control relay 42 to the supply 69 which relay thereupon operates.

Relay42, operated, closes the circuit between the siren 20 and the alternating current source 45.

Relay 6U", at its left-hand armature disconnects ground from the ringer I0 and at its right-hand armature prepares a shunt path across relay 62 from the winding of relay 40.

The siren 20 or other audible signal is actuated when relay 42 operates and its sound is picked up by the microphone 30 and sent over the line through the induction coil 44 to the attendant at the exchange who listens immediately after ringing to make certain that the siren is functioning. Actuation of key 36 in cord C connects the operators or attendants telephone across the tip an ring conductors of the connection. Y

The operator may now withdraw the plug II from jack I6 without affecting the operation of the audible signal 20 since relays 62 yand GIU are locked up. Condenser 12 in series with the secondary of induction coil 44 prevents the transmission of a line or cord signal and leaves the line clear for a call from the station S toy the exchange. l

If the subscriber at station S desires to silence the siren 2|), he removes the handset 9 from its switchhook thereby closing contacts '|3. I'he closure of contacts 13 causes relay 62 to be shunted so that this relay releases, opening the circuit to relay 6I) which relay also releases. Release of relay 62 disconnects battery from the microphone 3|), releases relay 42 and disconnects the secondary of induction coil 44 from the line `L. This removestone from the siren immediately, as it slows down gradually and the tone would otherwise interfere with the telephone conversation should the subscriber at station S desire to converse with the attendant at the exchange.

Release of'relay 60 reconnects ground to the station ringer ID and opens the shunt across relay 62 from relay 40.

Should the attendant at the exchange desire to test the siren he would cause the operation of the siren in the manner just described in connection with the broadcast of a re signal and listen in on the line. After listening for a few moments the attendant withdraws the plug from jack I6 and inserts it in jack I2 and rings out on the line. Relay 25 accordingly operates in the manner hereinbefore described and causes relay 4B to operate. The station ringer does not operate at this time asl its circuit to groundls held open at the left-hand armature of relay 60 yRelay 4I), operates, completes a shunt path across the winding of relay 62. including the front Contact and left-,hand armature of relay 60. Relay 62 accordingly releases, disconnecting the induction coil 44 from the line, opening battery to the microphone 30 and causing relay 42 to release. Release of relay 42 causes the siren 2D to be silenced.

Relay 60 does not release when relay 62 is shunted out but remains locked up until ringing current is cut off at the exchange. When ringing current is cut off, relay 40 releases and cuts off ground from the left-hand armature and front contact of relay 60 thereby permitting relay 60 to release.

The subscriber at station lS is provided with start and stop buttons by lvirtue of which thewsubscriber may initiate and terminate a lire signal.` Pressing thestart button 80 completes acircuit extending from groundedbattery, winding -o'f relay G, conductor G8, winding of relay 62, conductor 83, closed contacts of button 'to ground.4 Relays 60 and `:62 operate in this circuit and lock in the same manner hereinbefore described and perform the same functions, one of which is to eifect the operation of the siren 20. When the siren is started locally in this manner, no supervisory signal is transmitted to the attendant due to the presence of the condenser 12 in the induction coil circuit.

Pressing the stop button comp-letes a shunt circuit about the winding of relay 62 which relay releases and causes the release of relay Bll. The siren is accordingly silenced and the equipment restored to its normal condition.

`What is claimed is:

l.. In a combined telephone and fire alarm system, a central oflice, a subscribers station, a line circuit interconnecting said central oflice and said subscribers station, a signal located at a point remote from said subscribers station, and a switching device for causing the operation of said signal, said switching device being controlled from the central oflice by way of said line circuit or from the subscribers station.

2. In a combined telephone and fire alarm system, a central oflice, a subscribers station, a line circuit interconnecting said central office and said subscribers station, a signal located at a point remote from said subscribers station, and a relay adapted, when operated, to cause the operation of said signal, said relay being controlled either from said central ofce by Way of said line circuit or from` said subscriber s station.

3. In a combined telephone and fire alarm system, a central oiiice, a subscribers station, a line circuit interconnecting said central omce and said subscribers station, a signal located at a point remote from said subscribers station, a relay adapted, when operated to cause the operation of said signal, means at said subscribers station for causing the operation of said relay and means at said central office for causing the release of said relay subsequent to its operation from said subscribers station.

4. In a combined telephone and lire alarm system, a central office, a subscribers station,

a line circuit interconnecting said central office and said subscribers station, a signal located at a point remote from said subscribers station, a relay controlling the operation of said signal, a second relay, means at said subscribers station for causing said relays to operate and lock in. a series circuit, said second relay preparing a shunt for said iirst relay and said rst relay causing the `operation of said signal, and means controlled from said central oice for completing the shunt prepared by said second relay to cause the release of said rst relay and the effacing of said signal.

5. In a combined telephone and iire alarm system, a central oflice, a subscribers station, a line circuit interconnecting said central oice and said subscribcrs station, a signal located at `a point remote from said subscribers station,

a relay adapted, when operated, to effect the actuation of said signal, means at said subscribers station for causing the operation of said relay and other means at said subscribers station operable to shunt said relay.

6. In a combined telephone and fire alarm system, a `central office, a subscribers station, ailine circuit interconnecting said central oflice and said subscribers station, a signal `located ata point remote from said subsc'ibers station, a relay adapted,-when'operated, Vto eifect'tlieY actuation of' said signal, switching means at said subscribersstation for causing the operationof said 'relay and a -pairiof 'independent switching means at said subscribers station for shunting said relay to cause the deenerg'ization of said signal, one of said independent switching means being controlled by thereceiver switchhook at said subscribers station.

7. In a combined telephone and re alarm system, a central ofiice, a subscribers station, a line circuit interconnecting said central office and said subscribers station, a signal located at a point remote from said subscribers station, a relay controlling the operation of said signal, a second relay, means at said subscribers station for causing said relay to operate and lock in a series circuit, said second relay preparing a shunt for said rst relay and said rst relay causing the operation of said signal, a source of signaling current at said central office and means responsive to the transmission of current from said source over said line circuit for completing the shunt prepared by said second relay whereupon said first relay releases and causes the deenergization of said signal.

8. In a combined telephone and lire alarm system, a central office, a subscribers station, a line circuit interconnecting said central oice and said subscribers station, means for transmitting signal current over said line circuit by way of either the tip or ring conductors thereof, a signal normally responsive to the transmission of signaling current over said line'circuit by way of the ring conductor thereof and means eifectlve upon the transmission of signaling current over the tip conductor of said line circuit for rendering said signal unresponsive to a subsequent transmission of signaling current over said line circuit by way of the ring conductor thereof.

9. In a combined telephone and fire alarm system, a central oiiice, a subscribers station, a line circuit interconnecting said central office and said subscribers station, means for transmitting signaling current over said line circuit by way of either the tip or ring conductors thereof, a signal at said subscribers station, signal connecting means operating in response to the transmission of signaling current over the ring side of said line circuit for connecting said signal to the line circuit for operation, a second signal, and means including a pair of relays operating in response to the transmission of signaling current over the tip side of said line circuit for operating said second signal, one of said relays operating tc render said signal connecting means ineiective, upon a subsequent transmission of siginaling current over the ring side of said line circuit, in connecting said first-mentioned signal to said line circuit.

10. In a combined telephone and re alarm system, a central oiiice, a subscribers station, a line circuit interconnecting said central oflice and said subscribers station, means for transmitting signaling current over said line circuit by way of either the tip or ring conductors thereof, a signal at said subscribers station, means operating in response to the transmission of signaling current over the ring side of said line circuit for connecting said signal to said line cirover the ring side of said line for completing the shunt prepared by the other of said relays and to eiect a locking circuit for said other of said relays whereby said second signal is disabled and said rst signal maintained disconnected from said 5 line circuit.

RAYMOND C. BRADFORD. 

